A graduate of the USMA, West Point, NY in July 1846, George Brinton McClellan was appointed to the engineer corps brevet 2d lieutenant, and he served in the war with Mexico, 1846-48. He entered West Point as an instructor, and prepared a Manual on Bayonet Exercise, which became a textbook in the service.
When the Civil War started he was appointed major general of volunteers in Ohio. He was later made major-general in the regular army, and on the retirement of General Scott was made general-in-chief of the American army. He commanded the army of the Potomac in the protracted peninsula campaign. He won the battle of Antietam, and resigned from the army in 1864.
He was the Democratic candidate for President, but was defeated by Abraham Lincoln, who was re-elected. He published a number of books on military matters, and a Report on the Organization and Campaigns of the Army of the Potomac. He was Governor of New Jersey from 1878 to 1881.
Herringshaw's Encyclopedia of American Biography of the Nineteenth Century, Chicago, 1902, p. 631; Cullum Memorial Edition, Register of Graduates and former cadets, United States Military Academy, West Point, 1980, No. 1273.